Nitramino pyridine derivatives

ABSTRACT

HERBICIDAL ACTIVE NITRAMINOPYRIDINES OF THE FORMULA   R,R2,R3,(O2N-NH-)PYRIDINE   OR AN N-OXIDE OR SALT OF SUCH A NITRAMINOPYRIDINE BASE, WHEREIN R IS HYDROGEN OR ALKYL HAVING FROM 1 TO 6 CARBON ATOMS; R2 IS CHLORINE BROMINE, NITRO OR ALKYL HAVING FROM 1 TO 6 CARBON ATOMS; AND R3 IS CHLORINE, BROMINE OR NITRO BUT DIFFERENT FROM R2.

i St tes Peel U.s. Cl. 260296 4 Claims ABSTRACT OF Tl-IE DISCLOSUREHerbicidal active nitraminopyridines of the formula an N-oxideorsalt ofsuch; a nitraminopyridine base, whr ein-R'is hydrogenioralkyl havingfrom 1 to 6 carbon atoms; R isgchlorine,bromine, nitro or alkyl havingfrom l to6 carbonatorns; and R is chlorine, bromine v I v so includes aherbicidal composition comprising a pyridine baseadefined above or anoxide or salt of-j such a 'base,..in .admix t ure with a diluent orcarrier and a surface active agent.

.Suitable alkyl groups represented by R and R include metiiyh, ethylf,ist'a giror'n l v t-butyl-, p'entylr, hexyl-, and cyclohexyl.

The various groups-.R,--R ,;R and NHNO can occupy any positions in thepyridine ring: However, it is preferred thatwhere the -NHNO group: is inthe 4-position, the R -substituent should be in thex2-position, exceptwhere R -represents an +NO group when it preferably occupies the 3 or5-position; and-where the '-NHNO group is inmthe 2-position, the'R'-s'ubstituent is in the 4, 5 or 6.p;osition. -1 3:

z: Examples-of nitran'iinopyridinesof-this invention having ltra nnopyridine and itra nkinopyridine; and iii hi-oxides and salts'of theabove nitraminopyridine bases. A i i "5- y I The N-oxides ofthepresentmvention have the formula "ice mides, the sulphates and thesulphamates, and those with organic acids, for example the oxalates,chloroacetates and benzenes'ulphonates. Also included are the quaternaryammonium salts, for instance the alkyl and aralkyl pyridinium halidesand sulphates. The alkyl group attached to the nitrogen atom of thepyridine ring in an alkyl pyridinium salt can for example be one havingup to 20 carbon atoms, and the aralkyl group in an aralkyl pyridiniumsalt can for example be a benzyl or substituted benzyl group.

The nitraminopyridines of the invention may conveniently be made by theaction of fuming nitric acid on the corresponding aminopyridine in thepresence of sulphuric acid at a temperature below 15 C. The reaction ispreferably conducted at least initially at a temperature below 10 C.Where it is desired to substitute an NO group in the ring also, thereaction may comprise a second stage in which the temperature is raisedto from -60 to 100 C. The product yield obtained when the temperature ofthe reaction mixture is held below 10 C. for substantially the whole ofa reaction period of from 15 minutes to 6 hours is particularlysatisfactory.

A herbicidal composition of the invention can be liquid or solid, and aliquid composition can be a solution, suspension or emulsion. Often asurface active agent is present to stabilize the composition, tofacilitate its application, and/ or to improve biological activity.

A composition can contain a nitraminopyridine derivative as the onlyactive ingredient, or one or more other active compounds can be present.Thus the compounds of this invention may be used in combination withother herbicides in order to provide enhanced biological effectiveness.The use of various herbicides in combination at the time of a singleapplication or sequentially is common in practice. Herbicides which maybe used in combination with the compounds of this invention include butare not limited to: substituted phenoxyaliphatic acids such as 2,4dichlorophenoxyacetic acid; 2,4,5 trichlorophenoxyacetic acid, 2 methyl4 chlorophenoxyacetic acid and the salts, esters and amides thereof;triazine derivatives, such as 2 chloro 4 ethylamino6-isopropylamino-s-triazine; 2,4 bis-(isopropylamino)6-methoxys-triazine and '2 methylmercapto 4,6bis(isopropylamino)-s-triazine; urea derivatives such as 3(3,4-dichlorophenyl) 1,1 dimethylurea and 3 (m-trifluoromethylphenyl)1,1 dimethylurea and 3 (3,4-dichlorophenyl) 1 methoxy 1' methylurea;pyridylium derivative such as 1:1 ethylene 2,2 dipyridylium dihalide;lacetanilides such as N-isopropyl-a-chloroacetanilide, and 2' chloro2',6' diethyl-N-methoxymethyl acetanilide; acetamides such asN,N-diallyl a-chloroacetamide; carbamates such asethyl-N,N-di-n-propylthiolcarbamate, and 2,3 dichloroallyldiisopropylthiolcarbamate; substituted uracils such as 5 bromo3-secbutyl-6-methyluracil; substituted anilines such as N,N-diprOpYl-ogogoq-tllflllOlO 2,6 dinitro-p-toluidine; and pyradazonederivatives such as 5-arnino-4-chloro-2- phenyl-B- (,2H) -py'ridazione;

A solution of a nitraminopyridine derivative is one in an organicsolvent, for example an alcohol; a ketone; a hydrocarbon, for instancewhite spirit, solvent naphtha or kerosene; or a halogenated hydrocarbon,for instance perchloroethylene. Where a solution contains a surfaceactive agent, this is selected according to its solubility in thesolvent, and non-ionic surface active agents, for example ethers oresters of polyethylene glycols, are generally suitable.

Compositions that are suspensions can be simple ones of thenitraminopyridine derivative in an aqueous medium,

0 stabilized if necessary by the presence of a surface active agent, forinstance a non-ionic agent as exemplified above, or an ionic surfaceactive agent, for example a soap or' a synthetic material such as forinstance the sodium salt of a long-chain alkylated aromatic sulphonicacid.

A herbicidal emulsion of the invention is usually an aqueous emulsion,and can be obtained by emulsifying a solution of a nitraminopyridinederivative in a suitable organic solvent, generally one that iswater-immiscible, with water in the presence of a surface active agent.The surface active agent can be ionic or non-ionic in character.

Compositions which are solids can for instance be those in which thecarrier is an inert powder such as for instance kieselguhr or talc. Sucha solid composition may also contain a surface active agent tofacilitate its application and/or to improve its biological activity.

The proportion of the herbicide employed in the composition will ofcourse vary according to the nature of the composition and the proposedapplication. Compositions intended for direct application can contain,for example, from 0.001 to 2% by weight of nitraminopyridine and usuallycontain an amount within the range 0.01 to 1% by weight. Compositionsthat are concentrates and are intended to be diluted before use maycontain for instance from to 95% by weight of nitraminopyridine, forexample 25%, 50% or 80% of nitraminopyridine.

The dosage at which a nitraminopyridine derivative of the invention or aherbicidal composition containing such a nitraminopyridine derivativeshould be applied to obtain the optimum effect, will of course depend onthe particular crop concerned and the particular weeds that are to becontrolled. Also the activity or selectivity of a herbicide can bemodified according to whether it is applied to a pre-emergent orpost-emergen stage of plant growth. Normally, however, in foliartreatment for the modification of vegetative growth, thenitraminopyridines are applied in amounts from about 1 to about 50 ormore pounds per acre. In applications to soil for the modification ofthe growth of germinant seeds, germinative seeds, emerging seedlings andestablished vegetation, the nitraminopyridines are applied in amountsfrom about 0.1 to about 25 or more pounds per acre. In such soilapplication, it is desirable that the nitraminopyridines be distributedto a depth of at least 0.2 inches. In selective preemergence phytotoxicapplications the nitraminopyridines are usually applied in amounts fromabout 0.1 to 5 pounds per acre. It is believed that one skilled in theart can readily determine from the teachings of this specification,including examples, the general procedure for any application.

The invention is illustrated by the following examples.

EXAMPLE 1 This example describes the methods used to assess the contactherbicidal activity of compounds in greenhouse tests. The pyridinederivative to be tested was applied in spray form to plants of a givenage grown from seed in aluminum pans. After the plants were the desiredage, each aluminum pan was sprayed with a given volume of a 0.5%concentration solution of the test chemical, corresponding to a rate ofapproximately 10 lbs. per acre. This herbicidal solution was preparedfrom an aliquot of a 1% solution of the test compound in acetone, aknown amount of cyclohexanone-emulsifying agent mix, and sufficientwater to make up to volume. The emulsifying agent was a mixturecomprising 35 wt. percent butylarnine dodecylbenzene sulphonate and 65wt. percent of a tall oilethylene oxide condensate having about 6 molesof ethylene oxide per mole of tall oil. The injuries to the plants werethen observed approximately 14 days later and are reported in thefollowing table. The herbicidal ratings are defined as follows:

0No phytotoxicity 1-Slight phytotoxicity 2-Moderate phytotoxicity3Severe phytotoxicity 4-Death The nitraminopyridines tested were:2-bromo-5-chloro-3-nitraminopyridine (A)2-methyl-S-nitro-6-nitraminopyridine (B)2-methyl-3-nitro-6-nitraminopyridine (C) Compound Seed type A B 0Morning glory 3 4 4 Wild oat 1 0 0 1 1 2 EXAMPLE 2 This exampledescribes the production of 2-bromo-5- chloro-3-nitraminopyridine.

1.7 cc. of nitric acid (density 1.5) were added over a period of 20minutes to a stirred solution of 6 grams (0.029 mole) of 3-amino-2-bromo5-chloropyridine in 20 cc. of sulphuric acid (density 1.84) at 05 C. Thereaction mixture was held at this temperature for a further 2 hours andwas then poured into crushed ice, with the addition of dilute ammoniumhydroxide solution to a pH of 5, thus precipitating crude2-bromo-5-cl1loro-3-nitraminopyridine. The solid was filtered and washedwith water. After drying, the yield was 5 grams (68%) and the meltingpoint of the product was 111-1 14 C. (dec.). Crystallization from waterraised the melting point to 122 C. (dec.).

Found (percent): C, 23.6; H, 1.2; N, 16.3. C H ClBrN O requires(percent): C, 23.6; H, 1.2; N, 16.6.

EXAMPLE 3 This example describes the production of 2-methyl-5-nitro-6-nitraminopyridine.

16.7 cc. of fuming nitric acid (density 1.5 were added over a period of30 minutes to a stirred solution of 15 grams of2-methyl-5-nitro-6-aminopyridine in 60 cc. of sulphuric acid (density1.84) at a temperature of 4-8 C. The reaction mixture was held at thistemperature for a further 1% hours and was then poured into 200 grams ofcrushed ice. The product, crude 2-methyl-5-nit'ro 6- nitraminopyridine,was obtained as a precipitate, which, after the ice had melted, wascollected by filtration, washed and dried, to give a yield of 16.7grams. The meltingpoint, 123-125 C. (dec.) was raised by crystallizationfrom aqueous ethanol to 127 C. (dec.).

Found (percent): C, 36.6; H, 3.07; N, 28.3..C H N O requires (percent):C, 36.4; H, 3.0; N, 28.3.

EXAMPLE 4 2-methy1- 3 nitro 6 nitraminopyridine was obtained from2-methy1-3-nitro-6-aminopyridine by essentially the same method as thatdescribed in Example 3.

The crude product had a melting point of 118-120 C. (dec.) which wasraised to 126-127 C. (dec.) by crystallization from water.

Found (percent): C, 35.7; H, 3.0; N, 28.0. C H N O requires (percent):C, 36.4; H, 3.0; N, 28.0.

What is claimed is:

1. A compound of the formula a R NHN02 n a or an N-oxide or salt of saidcompound, wherein R is I hydrogen or alkyl having from 1 to 6 carbonatoms; R is References Cited chloride, bromine, nitro or alkyl havingfrom 1 to 6 carbon atoms; and R is chlorine, bromine or nitro butdiffer- 64192 s t 25 1967 cut from R with the further provision that atleast one of ep R2 and R3 must be 9 9 5 ALAN L. RO'IMAN, PrimaryExaminer 2. 2-bromo-5-chloro-3-mtrammopyr1d1ne. 3. Compound according toclaim 1 wherein R is chlorhm v US. Cl. X.R.

4. Compound according to claim 1 wherein R is 71--94; 260-294.8 R, 295 Sbromine. 1o

Talik et al., Chem. Abstracts, vol. 67, p. 6034, item No.

